Heat Illness or heat-related illness is a spectrum of disorders due to environmental heat exposure. Heat Illness can be deadly. The body normally cools itself by sweating. During hot weather, especially with high humidity, sweating isn't enough. Body temperature can rise to dangerous levels if precautions are not taken such as drinking water frequently and resting in the shade or air conditioning. Heat illnesses range from heat rash and heat cramps to heat exhaustion and heat stroke. Heat stroke requires immediate medical attention and can result in death.